The "Carriage" Showdown: Polyether vs. Polyester-While these materials do not determine yellowing caused by light exposure, they dictate stability under high-temperature and humid conditions. Even after the "locomotive" (base material) is selected, the choice of "carriage" (polyether or polyester component) can still become a weak link in specific environments.
1. Polyether-based TPU: Sensitive to high temperatures and prone to oxidation. Its advantages include excellent hydrolysis resistance-it does not hydrolyze upon prolonged immersion in water or contact with sweat-and superior low-temperature elasticity. Its drawbacks are a decline in mechanical strength at high temperatures and susceptibility to oxidation, which also reduces mechanical strength. When aliphatic polyether TPU is exposed to high temperatures (e.g., above 80°C) for extended periods, the polyether segments undergo thermo-oxidative degradation, resulting in a loss of surface gloss.
2. Polyester components-are they vulnerable to water and moisture? That statement is only half true. Standard polyester: Its hydrolysis resistance is indeed relatively poor, particularly in high-temperature, acidic, or alkaline environments. Under conditions of high heat and humidity, or upon contact with sweat or acid rain, polyester molecular chains are prone to hydrolytic cleavage; this leads to reduced strength and significant performance degradation, manifesting as surface fogging, whitening, tackiness, or even cracking. It is generally recommended for applications with a design lifespan of no more than two years. High-grade polyester: Structural modifications have been made to reduce the segments susceptible to hydrolysis, and hydrolysis-resistant additives are incorporated into the formulation, resulting in significantly better hydrolysis resistance compared to standard polyester. In work environments without frequent water exposure, it can remain functional for 5 to 8 years. It is typically used in applications involving exposure to oil or in dry environments.